yodeller vs vocalizer

yodeller and vocalizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
yodeller	Yes	No	No	No
vocalizer	Yes	No	No	No

As nouns, vocalizer is a hypernym of yodeller; that is, vocalizer is a word with a broader meaning than yodeller:

yodeller: a singer who changes register rapidly (popular in Swiss folk songs)
vocalizer: a person who sings

Other hypernyms of yodeller include singer, vocaliser, vocalist.

yodeller (noun)	vocalizer (noun)
a singer who changes register rapidly (popular in Swiss folk songs)	a person who sings
	an organism that can utter vocal sounds